Respect python_requires for test running

[cooperlees]

How is ptr not doing what you expect?

Today, ptr will not look at the python3 version and only run the the test suite if python_requires passes.

What is your suggestion to make this better?

Have the ast parser pull out python_requires if it exists (from setup.py + setup.cfg) and then skip a test suite if the requirement is not met.

• Try and look for upstream libraries to either vendor or include as deps for ptr to parse python_requires.
• This should be able to be disabled in the repo .ptrconfig

How can a developer reproduce this?

Run ptr on a Python 3.7 only project (stated via python_requires) with python3.6 ptr.